1. Field of the Invention
The present invention relates to a method and apparatus for feeding a component, and particularly to a component feeder by which an electronic component on a tray or an expanded sheet is picked up by a suction nozzle which is then turned over 180-degree so as to reverse the face of the picked-up component and is fed for mounting, and further to a component mounting method using such method and apparatus for feeding a component for carrying out component mounting operation onto the circuit substrate.
2. Description of the Related Art
In recent years, flip-chip mounting has become a main stream procedure in the field of semiconductor mounting technology as the miniaturization of a circuit substrate has been progressing as represented by a multi-chip module or a chip-size package.
An apparatus for flip-chip mounting is constructed such as shown in FIG. 3, in which an integrated circuit (IC) chip 102 located on a tray 101 with its circuit face upward is picked up by a suction nozzle 103, which is then rotated 180-degrees so as to turn over the IC chip 102 before feeding it to a mounting nozzle 104a of bonding head 104 which mounts the chip onto a circuit substrate 119.
Alternatively, as shown in FIG. 4 which illustrates another conventional component mounting apparatus, a chip 112 on an expanded sheet 111 is picked up by the suction nozzle 103, flipped by turning movement of the suction nozzle 103, and transferred to the mounting nozzle 104a.
The mounting nozzle 104a of the bonding head 104 attracts the IC chip 102 which has been reversed to have its circuit face downward, transfers it to a mounting position and mounts it on a prescribed location on the circuit substrate 119 with the circuit surface of the chip facing down. The IC chip 102 is then mounted on the circuit substrate 119 by connecting terminals on the circuit surface of the chip and a conductive pattern on the circuit substrate 119 by soldering or similar procedure.
The apparatuses shown in FIGS. 3 and 4 are capable of positioning the tray 101 or the expanded sheet 111 at a desired location in a Y direction, and for that purpose it is provided with a moving robot 105 for driving the tray 101 or the expanded sheet 111 in the Y direction. In addition, these apparatuses include another moving robot 106 for causing the suction nozzle 103 to move in an X direction which is orthogonal to the Y direction, so that the nozzle 103 can be positioned at a necessary location in the X direction. With this arrangement, an IC chip 102(112), wherever it is located on the tray 101 or on the expanded sheet 111, can be brought to confront a predetermined suction nozzle 103 and be picked up. The state of the IC chip 102(112) being positioned in relation to the suction nozzle 103 is monitored by a recognition camera 107. The suction nozzle 103 moves upward and downward for the action of picking up the IC chip 102(112), and such movement of the nozzle 103 is effected by a vertical motion mechanism 108 mounted on the moving robot For the purpose of reversing the face of the IC chip 102(112), the suction nozzle 103 is supported by a turning mechanism 117 which is mounted on the vertical motion mechanism 108 and has its turning center line Q which is orthogonal to a plane including an axis line P of the suction nozzle 103, so that a suction nozzle 103 facing down which has picked up an IC chip 102(112) can be turned 180-degrees around the turning center line Q and be faced upward.
In the above-described component mounting apparatus, it is often the case that the IC chip 102 at a prescribed position on the tray 101 as shown in FIG. 5A is displaced as shown in FIG. 5B due to vibration or the like during transfer of the tray 101. In order for compensating such displacement, the position of the IC chip 102 on the tray 101 is recognized by a recognition camera 107 before the suction nozzle 103 picks it up, whereupon a necessary amount of position correction is obtained from positional relationship between the center axis of the camera and the center of the IC chip 102, based on which the position of the suction nozzle 103 is adjusted in X- and Y- directions. The position of the IC chip 102 in relation to the suction nozzle is thus corrected before it is picked up.
However, in case IC chip 102 is displaced at a predetermined angle in a rotating direction, even with the above described position correction in X- and Y- directions, IC chip 102 is not in register with the tip of the suction nozzle 103 as shown in Fig. 5C. Picking up of an IC chip in such condition with the suction nozzle 103 may cause a risk that the suction surface of the nozzle 103 hits the circuit surface of the IC chip 102 rather than bump portions 120, resulting in a flaw or damage on the circuit face of the IC chip 102.
In another component mounting apparatus shown in FIG. 4, a diced wafer 113 is placed on the expanded sheet 111 which is given tension and separated into individual chips 112 by means of expansion of the expanded sheet 111. Here, position correction is necessary since the wafer 113 itself may be displaced in relation to the expanded sheet 111, or each of the chips 112 may be displaced in X- and Y- directions and/or in rotating a direction due to unevenness in the expansion of the expanded sheet 111.
Furthermore, there have been demands that the IC chip 102(112) must be picked up with the suction nozzle more precisely at a predetermined position for the following reason. After the component has been fed from the suction nozzle 103 to the mounting nozzle 104a of the bonding head 104, the circuit surface of the IC chip 102(112) is recognized again on its way to the mounting position so as to inspect the condition of bumps or the position of circuits with another recognizing camera 117. Such recognition is made with a higher number of pixels in this camera in order to accurately recognize electronic circuits which have become more and more complex due to miniaturization of circuit substrates in recent years. There is thus a problem that the IC chip 102 held with the mounting nozzle 104a of the bonding head 104 may not come into the field of view of the recognizing camera if the IC chip 102 is displaced from a predetermined position on the mounting nozzle 104a. 
An object of the present invention is to provide a method and apparatus for feeding a component by which components can be picked up precisely at a predetermined position even when a target component is shifted at a certain angle around the axis line of the suction nozzle.
Another object of the present invention is to provide a method for mounting a component using such method and apparatus for feeding components by which the number of errors in a mounting operation can be reduced.
In order to achieve the above objects, in a component feeder which picks up a component arranged in a row from above with a suction nozzle and turns over the suction nozzle upwards by 180-degree rotation so as to feed the component of which face has been thereby turned over, the present invention is characterized by having: a rotary mechanism mounted on a turning mechanism which causes the suction nozzle to turn, by which the suction nozzle is rotated around an axis line thereof; a detector which detects an amount of displacement of the component in a rotating direction around the axis line of the suction nozzle which is going to pick up the component; and a controller for controlling the rotary mechanism such as to cause the suction nozzle to rotate at a necessary angle around the axis line thereof before picking up the component according to detection results.
The method of feeding a component according to the present invention comprises the steps of: detecting an amount of displacement of the component in a rotating direction around the axis line of a suction nozzle which is going to pick up the component before the suction nozzle picks up the component arranged in a row; rotating the suction nozzle around its axis line at a necessary angle according to detection results so that the component is located at a correct position in relation to the suction nozzle; picking up the component with the suction nozzle; and turning over the suction nozzle upwards by rotation of 180-degrees so as to feed the component of which face has been thereby turned over.
With such an arrangement, since an amount of displacement of the component in a rotating direction which is picked up next is detected by the detector, and the controller controls such that the rotation mechanism causes the suction nozzle to rotate at a necessary angle in accordance with the detection result, the suction nozzle can always pick up the component which is exactly at a predetermined position in terms of its angle around the axis line of the suction nozzle. The suction nozzle is thus prevented from hitting against the circuit face of the component which may cause a chip or a flaw on the component.
It is possible to mount on the turning mechanism a plurality of suction nozzles disposed radially around a turning center line of the turning mechanism. Component pick-up operation can be thereby efficiently carried out by successively using the plurality of suction nozzles. Alternatively, the plurality of suction nozzles may be separately used corresponding to different kinds of components so as to appropriately deal with various types of components.
Moreover, in order to achieve the above objects, the method of mounting components according to present invention comprises the steps of: before picking up the component arranged in a row from above with a suction nozzle, detecting an amount of displacement of the component in a rotating direction around the axis line of the suction nozzle which is going to pick up the component; rotating the suction nozzle around its axis line at a necessary angle according to detection results so that the component comes to locate at a correct position in relation to a predetermined posture of the suction nozzle; picking up the component with the suction nozzle; returning the suction nozzle to its predetermined posture; turning over the suction nozzle upwards by rotation of 180-degree so as to flip the component; transferring the component from the suction nozzle to a mounting nozzle; recognizing conditions of the component held with the mounting nozzle on its way toward a mounting position on a circuit substrate with a recognizing means; correcting the position of the component in accordance with recognition results; and mounting the component on the circuit substrate.
According to the above method, since the displacement of the component in a rotating direction around the axis line of the suction nozzle, which is going to pick up the component, is detected and corrected by rotating the suction nozzle at a necessary angle, it is possible to pick up the component precisely at a predetermined position, by which it is prevented that the component comes out of the field of view of the recognizing camera when the condition of the component is recognized again after it has been fed from the suction nozzle to the mounting nozzle, ensuring that the position of the component to be mounted is certainly recognized. The number of errors in mounting operation can be thereby reduced and production efficiency is increased.